DE3530593A1 - MACHINE TOOL AND METHOD FOR OPERATING SUCH A MACHINE TOOL - Google Patents

Description

Machine tool and method for operating such a machine tool

description
10

The invention relates to a machine tool according to the preamble of claim 1 and a method for operation such a machine tool.

When drilling with a machine tool, a cutting tool is generally used in discrete, sequential Steps introduced into a workpiece. With every step that the cutting tool takes into

piece is advanced, chips must be removed from its material. At the end of each of these steps the cutting tool is at least partially withdrawn from the workpiece in order to use the cutting tool

To cool cutting oil.
25th

With progressively deeper insertion of the cutting tool it becomes more and more difficult to remove or eject chips into the workpiece. Besides, it will be for that Cutting oil more and more difficult to get the cutting tool

enough if this penetrates the workpiece. So when the cutting tool is advanced into the workpiece the rate of advance of the cutting tool into the workpiece should be gradually decreased.

In the prior art, the need has already been recognized to reduce the feed rate of the cutting tool, if this penetrates the workpiece. For example, in Japanese Patent Application Laid-Open No. 223508/1983 stated that the first discrete feed step for a cutting tool in a Workpiece or at least the first few such feed steps over a predetermined distance should take place. Thereafter, the feed distance of the cutting tool into the workpiece is determined on each successive one Step reduced in a geometric relationship. This method of reducing the feed rate however, a cutting tool has several disadvantages. Special knowledge is required once, to set the predetermined advance distance for the first few steps. Second is the number of discrete steps required to perform an operation are larger than ideally for that respective cutting tool required minimal number of steps, since the cutting tool with a distance into the workpiece which changes as a function of the total depth of advance when a cutting tool is advanced large diameter and high strength is used. The efficiency is therefore below the optimum Value.

The present invention therefore has the task of specifying a machine tool of the type mentioned above, in which a high-efficiency cutting tool is implemented in a series of discrete steps Workpiece is advanced; in addition, a method for operating such a machine tool is to be specified will.

This object is achieved by the invention described in claims 1 and 10; Refinements of the invention are given in the dependent claims.

The machine tool according to the invention uses a data memory in which a constant value for each of the Feed steps are saved with which a cutting tool is advanced step by step into a workpiece, as well as arithmetic devices, which for each of the individual steps a feed value as a function of this Step calculates the stored constant value and a variable factor that controls the operation of the cutting tool influenced. After all, in the tool

XO machine control devices are provided with which the Cutting tool advanced into the workpiece in a number of steps as a function of the feed rate is at least partially pulled out again after the end of a feed step and then to be reinserted into the workpiece as a function of the feed rate for the next step. The variable Factor affecting the operation of the cutting tool is preferably either diameter of the cutting tool or a material coefficient of the workpiece.

The diameter of the cutting tool is used as a variable factor is selected, the feed rate is calculated as a function of both the diameter of the cutting tool as well as the corresponding constant value for this feed step. Is the material coefficient of the workpiece is the variable factor, the feed rate is calculated as a function of the material coefficient of the Workpiece and the corresponding constant value for this feed step.

In one embodiment, the storage devices a first constant value for each step and a second constant value (material coefficient of Workpiece) for each of the different workpiece materials stored. In this embodiment, for

each of the discrete feed steps a feed value as a function of the diameter of the cutting tool, the first constant value for this step and the second constant value for the relevant material of the Workpiece calculated.

Machine tools according to the present invention operate with high efficiency and are easy to operate. Entering the parameters required for the respective task into the machine is easy and can are carried out by operators who have no special knowledge, for example NC programming languages.

Embodiments of the invention are explained in more detail below with reference to drawings. Show it

Fig. 1 is a cross section of the structure

a machine tool is shown, which is used to implement the present

Invention can be used;

Fig. 2 is a perspective view of the exterior

the machine tool of FIG. 1; 25th

Fig. 3 is a graphic representation of the movement

a drilling tool according to the present invention;

Figure 4 is a graph of constants

Values used in a drilling operation according to the present invention will;

Figure 5 is a graph of constants

Values, which according to the present invention

finding in a thread cutting operation

be used;

6 is a graphic representation of the movements of a thread cutting tool according to FIG

present invention;

7 shows a diagram with material coefficients

of workpieces;
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8 is a block diagram of a system in accordance with

of the present invention;

Figure 9 is a block diagram of a preferred embodiment of the present invention;

Fig. 10 is a flow chart of a drilling operation

according to the present invention;

11 is a flow chart of a thread cutting

operation according to the present invention;

Fig. 12 is a front view of an operator panel (Control terminal), which together

can be used with the present invention; and

Fig. 13-19 various entries that appear on the screen of the control terminal of

Fig. 12 may appear to enter information derived from the present Invention can be used.

1 shows a cross-section, viewed from the side, of a machine tool 10 which is used to implement the Teachings of the present invention can be used. The machine tool 10 is preferably with an automatic Tool changing device and includes a feed screw 12 driven by a feed motor 14 is rotated. A spindle head 16 is mounted so that it is through the feed screw 12 in both vertical directions can be moved. A spindle motor 18 is mounted on the spindle head 16. Of the Spindle motor 18 drives a spindle 20. The spindle 20 in turn is designed so that it is a cutting tool, for example a drill 22, which in turn is driven by the spindle motor 18 in a known manner is driven. A tool magazine 24 is secured in a tool holder 26 that the magazine can rotate to certain positions indicated by the index. The tool holder 26 is also like that supported so that it can move along the axial direction of the spindle 20.

In FIG. 2 there is a cover over the tool magazine 24 28 attached. The machine tool 10 also includes a frame 30 on which with the help of a holding arm 34 a computer 32 can be attached. The computer 32 includes a keyboard 36 and a memory random access (RAM), a read-only memory (ROM) and a central processing unit (CPU) whose Functions will be described in detail later.

In normal operation, the machine tool 10 cuts a hole in a workpiece using a cutting tool to such as a drill 22. This cutting process can be carried out as shown in FIG Fig. 3 in a series of consecutive

Steps. At the end of each step N, the cutting tool, such as the drill 22, has penetrated the workpiece (not shown) _{over a distance X n.} After completing this step, the cutting tool is at least partially pulled out so that cutting oil can be supplied to the cutting edge of the cutting tool. Then, in the next incremental step, the cutting tool is advanced into the workpiece _{over a new distance X n + 1 , where X "1 is} greater than X. This process of advancing the cutting tool in increments into the workpiece is continued until the desired cutting distance has been reached.

The present invention is based on the knowledge that the diameter D of the cutting tool should have an effect on the distance X _n of each feed into the workpiece, since the cutting operation is the more effective and the feed can take place at a certain step N, the deeper the diameter of the cutting tool is larger. It has also been found that the ratio between the feed distance X _n for any given step N and the drilling diameter D has a certain value if the most effective feed distance X _{n is to be} achieved, regardless of the diameter D of the drill for a given type of material Workpiece. Although the ratio of IL to D slowly decreases when the number N of steps increases, the ratio X _n to D gives a saturation curve that can be used in connection with any drill diameter D to obtain the ideal feed distance for any feed step N. To determine X _n. In addition, it has been found that this relationship between the feed _{distance X n} and the diameter D of the cutting tool applies to both drilling tools and tools which cut threads in boreholes.

Finally, it was found that each workpiece can be assigned a material coefficient that differs from that of the Depends on the material from which the tool is made. This material coefficient of the workpiece can be independent of the diameter of the cutting tool used. In addition, this material coefficient of the workpiece in the computer 32 can be used to determine the distance X for any step in the cutting process to be changed so that the ideal value X ^ results for the workpiece material in question. Ideally X "can be calculated as a function of a constant Value in the form of the ratio X «/ D for step N times that Diameter D of the cutting tool used times the material coefficient of the workpiece.

For example, Fig. 4 shows specific constant values (5.0, 9.5, 12.5, 14.7, 16.2, 17.5, 18.5, 19.1, 19.6, 20.0) for each feed step N = 1 to N = 10. As mentioned above, each of these can constant values are understood to be the ratio of the ideal effective cutting length X "for represents a given diameter D of the cutting tool for each step N. So if any of the constant values shown in the illustration of FIG. 4 for the feed with the diameter of the cutting tool is multiplied, one obtains the idealized feed cutting length X for a certain step N.

As mentioned above, the constant values shown in FIG. 4 relate to a drilling tool. Comparable constant values are shown in FIG. 5 with respect to a Tapping tool for drill holes shown.

FIGS. 3 and 6 illustrate the preferred movement of a cutting tool when that indicated in FIGS constant values are used for a drilling tool

or a thread cutting tool. In FIG. 3, a first feed distance X _n extends from a starting point P .. into a workpiece. X is calculated by multiplying the diameter of the drill with the given constant value (5.0 for step N = 1). The drilling tool is then at least partially withdrawn from the workpiece. According to the illustration in FIG. 3, the drilling tool can also be completely removed from the workpiece. Then the drilling tool is again introduced into the workpiece and that _n over a distance ^ _{+ 1} / which distance X. is calculated by multiplying the constant value (9.5 for step N + 1 = 2) by the diameter of the drilling tool. This process is then continued until the desired cutting depth has been reached in the workpiece. In Fig. 6 a comparable movement for a thread cutting tool is shown. In the example there, however, the cutting tool is only partially pulled out of the workpiece after each step.

At a later point there is a more detailed description of the mode of operation that is required to implement the To achieve movement of the cutting tools according to FIGS.

As mentioned above, the material coefficient of the Workpiece can be used to calculate the specific distance with which a cutting tool enters a workpiece must be introduced at a certain step N. According to a preferred embodiment According to the invention, the distance X is determined simply by a constant value (such as in the graphic Representations of FIGS. 4 and 5 indicated) at a certain step N both with the diameter D of the used Cutting tool as well as by the material coefficient of the workpiece (for example the

Coefficients shown in Fig. 7 for certain workpiece materials are specified).

The constant values of FIGS. 4 and 5 can be determined experimentally for a standard workpiece material, for example carbon steel S45C, the value 1.0 then being assigned to this material coefficient. Of the
Coefficient for softer workpiece materials will then have values greater than 1.0, while the coefficient for materials harder than carbon steel S45C
are has values smaller than 1.0. Although certain coefficients are indicated in FIG. 7, the material coefficients of the workpieces used for each embodiment of the invention can be determined experimentally.

8 shows a block diagram of the general structure of a machine tool made in accordance with the teachings of the present invention Invention is designed. According to FIG. 8, there are provided: a data storage device 50 which operates in this way

will that they are for each a multitude of discrete

Cutting steps stores a constant value. Computing devices 52 responsive to the value of a variable factor affecting the operation of a cutting tool, for example the diameter of the cutting unit

stuff or the material coefficient of a workpiece, and which calculate a feed rate for each of the discrete steps as a function of the corresponding in
5 data storage device 50 stored constant value for this step and the value of the variable

Factor, for example the diameter of the cutting tool or the material coefficient of the workpiece (or both). 8 also shows a control device 54 with which a cutting tool can be advanced into a workpiece, as a function of the determined by the computer devices 52

Feed values for each of a plurality of steps N; also cause the control devices 54. that upon termination of the feed for one step, the cutting tool is at least partially pulled out of the workpiece and then penetrates the workpiece again, with a feed rate determined by the feed rate the next step is determined. The actual movement of the cutting tool is determined by the Caused feed motor 56, which is influenced by the control devices 54.

Figure 9 shows a specific preferred embodiment of the present invention. There is a store there 60 shown with random access, in which a constant value is stored for each step of a cutting operation can be. For example, if the cutting operation is drilling, then constant Drilling feed values, as indicated in FIG. 4, are stored in part 62 of RAM 60. Concerns the cutting operation the cutting of threads, constant values for the feed rate for thread cutting are used instead stored in part 64 of RAM 60 as shown in FIG. There are also material coefficients of the workpieces, as shown for example in FIG. 7, are stored in the part 66 of the RAM 60. A machining program is stored in part 68, and a standard feed constant for drilling is stored in part 70 and in part 72 a standard feed constant for thread cutting. The function of the standard feed rate constants for drilling and thread cutting is described in more detail below.

The machining program stored in part 68 of the random access memory 60 can be activated by actuation the keyboard 36 of the computer 32 shown in FIG. 2

can be entered. To change a machining program, the keyboard 36 can be operated so that it changes or adds a step for entering drawing data, for example the diameter of tools or holes, a step for determining the machining sequence, a step for changing the tool pattern Step of assigning and changing tools, one step of changing cutting conditions, one step to display the elimination or arrangement of capacities that are vecwaxfet or nkht in the programs and memories stored in the RAM 60 and a step of transferring data from and to the internal program memories .

Figure 9 also shows read-only memory 74 ^{which is used in} connection with actual control of the position of the cutting tool, as is known in the art of indexed machine tools.

FIG. 9 also shows a central processing unit 76 of the computer 32 from FIG. 2, a keyboard 36 of the computer 32, a feed motor 14 as shown in FIGS. 1 and 2, and a spindle motor 18 as shown in FIG is also known from Figs.

An actual drilling operation according to an embodiment of the present invention can be performed according to The flowchart shown in Fig. 10 can be executed. The flow chart of Fig. 10 is specifically designed for a drilling operation, while the flow chart of Fig. 11 specifically intended for a thread cutting operation is.

As shown in FIG. 10, a first relates to

Instruction 101 the step in which the diameter of the cutting tool and the material type of the workpiece are determined. These data can be obtained by operating the keyboard 36 of the calculator 32, as will be explained in detail later. By way of illustration, it is assumed as an example that as a result of instruction 101 a diameter of the cutting tool of 4 (4.0) mm was obtained, and that aluminum is present as the material of the workpiece.
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In instruction 102 the material coefficient for the workpiece made of aluminum is read from part 66 of RAM 60. In the case of aluminum, this coefficient is 2.0 as shown in FIG. 7.

In step 103 the spindle motor 18 is switched on.

Instruction 104 starts the actual feed movement in order to quickly move the tip of the cutting tool to the starting point P ₁ of FIG. 3 immediately adjacent to the

To guide workpiece. This feed is carried out with the aid of the feed motor 14, as in the state of Technology is known.

Instruction 105 requires reading out the first constant value (X / D) of the feed for the first step N = 1. According to FIG. 4, this value can be 5.0.

The first feed value is received in instruction 106, by dividing the first feed constant (5.0) with the tool diameter (4.0 mm) and the material coefficient of the workpiece (2.0) is multiplied to obtain a first feed value of 40.0 mm.

Branch instruction 107 determines whether the first

Feed value (40.0) is greater than the machining depth, for example 85 mm. If the answer is "no", instruction 108 is executed. Depending on instruction 108 the feed is carried out over a distance, which is determined by the first feed value (40.0 mm) with the feed speed of the machine. The respective processing step that has just been carried out is registered in instruction 109. In this example the value of N was found to be 1.

Instruction 110 causes the number of steps to be increased by 1, so that the next sequential step can be undertaken. In the example under consideration, the value of N is 110 after the instruction has ended equal to N = 2.

Instruction 111 causes the cutting tool to be quickly withdrawn from the workpiece, to a position P ₁ which is immediately adjacent to the workpiece. At this point, cutting oil can be fed to the cutting tool.

Instruction 112 causes the drill to quickly up to the previous feed value (40.0 mm) minus a tolerance value 1 is introduced, which for example 1.0 mm.

As a result of instruction 113, the feed constant for the next step (N = 2) obtained from part 62 of random access memory 60. According to Fig. 4 this next constant is equal to 9.5.

In step 114, a calculation is made to obtain the to get the next feed rate. To do this, the feed rate for the Nth step is obtained by adding the

The feed constant for the N-th step from FIG. 4 (9.5 for N = 2) is multiplied by the material coefficient from FIG. 7 (2.0 for aluminum) and with the drilling diameter D (4.0 mm). For the second step, the example values given above therefore result in a feed value for the second step X_ of 9.5 2.0 4.0 = 76 mm. In addition, since the cutting tool has already been returned to the feed rate X ₁ -I mm in instruction 112, instruction 114 has the effect that the additional incremental distance is determined which the cutting tool must cover, namely X-,. - X _n + 1 or in the example 76 mm - 40 mm + 1.0 mm = 37 mm.

Branch instruction 115 determines whether the feed rate X for the Nth step is greater than the desired one total processing depth. If the result is negative, instruction 116 is executed, so that the feed rate accordingly the Nth step occurs at machine speed and the program returns to instruction 110. In this case, instructions 110 to 115 are executed again.

However, if 115 determines that the Nth feed value is greater than the feed depth, instruction 117 is executed. In this case the feed takes place up to the desired total processing depth according to the execution of instruction 117. Then instruction 118 causes the cutting tool is returned to the starting position and instruction 119 stops rotating the spindle.

If the feed rate for the first step is greater than the total machining depth, the result will be of instruction 107 to "Yes", instructions 108 to 115 are skipped and instructions 117 -

119 executed with priority.

According to the embodiment described above Even a person inexperienced in drilling can set the feed data according to the diameter of the drill and / or Adjust the material of the workpiece used to an optimal Weirt. During the drilling process can therefore Number of feed steps can be reduced to a suitable value. In other words, drilling can take place with high efficiency.

In addition to the previously described preferred embodiment with regard to drilling, there are many Modifications possible. For example, the feed values can also only correspond to the material coefficient of the workpiece, although it is advantageous that in the variable factor the diameter of the cutting tool is taken into account. In this regard, it is necessary to set a default value in part 70 of memory 60 for the drilling feed constant. Then the standard value for the drilling feed constant takes over the role of the diameter of the cutting tool, usually entered when executing instruction 110 would have been. Accordingly, the first feed value would be obtained by executing instruction 106 becomes equal to the standard value for the drilling feed constant times the first feed constant (5.0) for the first step times the material coefficient of the workpiece (2.0). So it goes without saying it is preferable not to use the default value for the feed rate and use the actual one instead To determine the diameter of the cutting tool and to use it.

It is also possible to use the present invention

add without affecting the material coefficient of the workpiece To make use of it. In such a case, the material coefficient for the workpiece can be set to 1.0 so that it actually does not play a role in the calculation of the feed values. The feed rate is then only a function of the diameter of the Cutting tool and the corresponding constant values shown in FIG. 4 for the particular step carried out are shown.

Fig. 11 shows a flow chart of another embodiment of the present invention. In the flow chart of Fig. 11 is a tapping operation in one Drilled hole carried out, instead of the drilling process, the Fig.

underlying. The instructions that come with the threading operation are similar to those that occur when drilling. In that regard, they are Instructions 201 to 210 are identical to instructions 101 to 110. In instruction 211, however, the main spindle becomes rotated in a direction opposite to the cutting direction so as not to close the thread grooves destroy generated on the inner surface of the tool.

Also, in a threading operation, the amount is of the ejected chips are relatively small. The cutting tool is therefore only pulled out of the workpiece by a small distance, for example distance 1, the is shown in FIG. When the cutting tool is pulled out over a distance 1, the cutting tool remains actually within the workpiece. Instruction 212 resumes normal rotation. Additionally Instruction 218 requires a return to a starting point with the spindle rotating in the opposite direction will. Other than these differences, instructions 213-219 are essentially identical

• ■ ■
f '' ■ '. 1 with instructions 113 to 119 of FIG. 10.

The embodiment of FIG. 11 has advantages because

\ . '■■■■ the feed rate values for the diameter of the thread ■:. '5 bore can be set to the most suitable value ■ f>; I) ■■) and since the number of feed steps is reduced to one, {.. ■ '.V! appropriate value can be reduced so that the '../'/ thread cutting operation can be carried out quickly and with high efficiency.
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As in the case of a drilling process explained above, a thread cutting operation can either only be carried out with one Variables of the thread cutting diameter and / or only with one variable of the material coefficient of the workpiece be performed. If only the thread cutting diameter is variable, the material coefficient of the workpiece can be set to the value 1.0. If only the material coefficient of the workpiece is variable, can use a standard thread cutting feed rate instead of the Ge thread cutting tool diameter variables are stored in part 72 of RAM 60.

In summary, the present invention relates to a machine tool for machining the workpiece, by using a cutting tool, for example a drill or a? Taps in a range of discrete Steps into a workpiece is advanced. The machine tool contains a data memory in which at least a first constant value is stored for each of these steps. Another calculation mechanism used responds to the value of a variable factor that determines how the cutting tool works influences, for example the diameter of the cutting tool or a material coefficient of the workpiece, a feed value for each of the discrete steps

to be calculated as a function of the associated constant for this value and the value of the variable factor, namely the diameter of the cutting tool or the material coefficient of the workpiece. In the end a control mechanism is used to control the cutting tool as a function of the feed rates for a variety of these steps into the tool and after the end of the feed for at least one step can be partially pulled out again; then the control mechanism causes the cutting tool to function of the feed rate of the next step is reintroduced into the workpiece.

As an example, Fig. 12 shows a front view of the calculator 32. As mentioned above, the calculator 32 has a keyboard 36 on. The computer 32 also contains a cathode ray tube (screen) 316. The computer 32 controls the display on screen 316; in addition, as shown in FIG. 12, it contains a key 341 for an editing mode, ten numeric keys 342, and a setting key 343.

For example, when the key 341 for the program edit mode on the keyboard 36 is pressed, appears on the screen 316, the display shown in FIG. This display can e.g. B. seven (7) menus as shown in Figure 13, with the various numbers on each of these menus Flashing can be set »In the event that the entire machining operation is to be performed as indicated by cursor (position indicator) 316a is required, the processing data should be entered according to menu no. That's why the Key 1 of the ten numeric keys 34 2 and the setting key 343 of FIG. 12 are pressed to enter the input

mode for the processing data. The screen 316 shown in FIG. 14 is then obtained Display and cursor 316a prompts entry of a program number. If a program number, e.g. B. 1000 is selected, this number is set using the ten numeric keys 342 and the set key 343 entered. The program number is then shifted to the program display area as shown in FIG and requires input data to determine the origin of the X value. If this is known he will entered. However, if the X value is not known, the setting button 343 is pressed. In the next step you are asked to enter the origin for the Y value of the machining operation. It therefore becomes more similar When the set button 343 is pressed, the image on the screen 316 changes to that shown in FIG Format changes. In this condition, the display 316 requires that the number of workpieces used be entered will. When this number is equal to 1, the digit "1" is entered using the numeric keys 342 and then the set button 343 is pressed. If the number of workpieces is greater than one (for example up to four are allowed), an entry is required for each workpiece.

Subsequently, the display on the screen 316 changes according to FIG. 17, where the type of used Material of the workpiece must be entered. If the material is S45C, the number becomes "1" is selected from the menu shown in the lower part of the display on screen 316 and with Entered using numeric keys 342; then the setting button 343 is pressed again.

The display on the screen will change

to the format shown in FIG. The display shown in Fig. 18 prompts you to enter the type of processing required in the first operation. In the event that a hole is to be drilled in the first operation, enter the number "2" and then press the setting key. As a result, the display on the screen 316 assumes the format shown in FIG. In the format of Figure 19, cursor 316a prompts input of the hole diameter. XO ^ ⁿ the example discussed above with a hole diameter of 4 mm is thus using the numeric keys

342 enter the value 4.0 and press the setting key again

343 pressed.

Now the operation can be performed, which drills holes with a diameter of 4.0 mm. In practice, however, the following additional data should be entered:
An indication of the roughness of the machined surface; an indication of the processing pattern, e.g. B. that the drilling is to be performed along a circumference or along the four sides of a rectangle or in a straight line and the spacing and angles of the pattern; an indication with respect to the vertical axis (Z-axis) whether the pattern is a through hole or a blind hole; an indication of the total machining depth (e.g. 85 mm according to the example explained above); an indication of the height of the workpiece; and an indication of the return height.

After the drilling program has been set up as described above, drilling can be carried out according to the in 10 and 11 shown in the flow charts will.

The dimensions to be entered are final values. For the Case that the machining on an ordinary, conventional numerically controlled machine tool (NC), it is therefore necessary that the program receives the data about the bearings into which the workpiece is to be moved, as well as about the speed the movement of the workpiece, the tools to be used, the speed of the spindle, etc; these Data must then be converted into NC language and incorporated into the program of the NC machine tool. The NC programmer of such conventional systems must therefore be in the field of machining techniques and be familiar with the NC language.

In a machine tool according to the present invention, however, no NC language is used and the input of the machining conditions and similar data is separate from the program editing process which was described above with reference to FIGS. 13 to 19. Therefore, at the time such programming is performed, any person who can properly read a technical drawing can perform the program editing. That is, all that is asked of the programmer is, in sequence, the final machining operation. and enter the relevant dimensions according to the questions displayed on the screen. The programming by the operator of the machine tool can therefore be carried out with ease. The order of use of tools, machining conditions, selection of tools and the like for the machining operation can be separately inputted as data for the machine tool. In addition, the data for the programs can be modified so that they are stored in: \] s Tc-i lc Ici program.

BATH

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Claims (17)

e - European'Patent Attorneys e *? 'D-8000 Munich 19!': H «mi u: i- O I'- |.>, .. iji ί) ι (·,! Ϊ́) ΐι; pi-v.ikf ·· Ar> ton Frt'ihe'f p! ^ those before · Pt-i 'P: p! .- lng fir Dr Woifgang VVaD'a: Dip' -Chem 26 August 1985 D / we -T. B 4452-D 10 BROTHER KOGYO KABUSHIKI KAISHA No. 35, Horitadori 9-chome, Mizuho-ku, Nagoya-shi, Aichi, Japan Machine tool and method for operating such a machine tool 25 claims 1. Machine tool for machining a workpiece with a cutting tool that is inserted into the workpiece in a series of discrete feed steps where the machine tool includes storage devices and computing devices, characterized by the following features: 35 a) constants (62, 64) are stored in the storage devices (60) for each of the feed steps, b) Computing devices (76) read the stored constants from the at each processing step Storage device and link it multiplicatively with at least one variable factor, which determines the operation of the cutting tool in order to assign a feed value for each feed step determine, and c) control devices (54) are provided which rotate the cutting tool at each feed step move the calculated feed value and after completing each feed step the cutting tool at least partially out of the workpiece and then as a function of the feed rate for insert the next feed step back into the tool. 2. Machine tool according to claim 1, characterized in that that the variable factor is the diameter of the cutting tool. 3. Machine tool according to claim 1, characterized in that that the variable factor is a material coefficient of the workpiece. 4. Machine tool according to claim 3, characterized in that that the material coefficients of various workpieces are stored in the storage device. 5. Machine tool according to claim 1, characterized in that that the variable factor is the product of the diameter of the cutting tool and the material coefficient of the workpiece. 6. Machine tool according to one of claims 1 to 5, characterized in that the constant for all feed steps is equal to. 7. Machine tool according to one of claims 1 to 5, characterized in that the material coefficient is the same for all workpieces. 8. Machine tool according to one of claims 1 to 7, characterized in that the cutting tool is a Drill is. 9. Machine tool according to one of claims 1 to 7, characterized in that the cutting tool is a tap. 10. A method of machining a workpiece with a cutting tool that is in a series of discrete Feed steps is introduced into the workpiece, characterized by the following process steps: a) Find a constant for the length of each Is determining the feed step (Fig. 4; Fig. 5); b) Calculating the feed value for each feed step by multiplying the Constants for this feed step with a variable factor that determines how the cutting tool works certainly; and c) advance of the cutting tool according to the determined advance value and then, at least partial retraction of the cutting tool and renewed advancement as a function of the feed value for the next feed step. 11. The method according to claim 10, characterized in that the variable factor is the diameter of the cutting tool is. 12. The method according to claim 10, characterized in that that the variable factor is the material coefficient of the workpiece. 13. The method according to claim 10, characterized in that that the variable factor is the multiplicative link between the diameter of the cutting tool and the material coefficient of the workpiece. 14. The method according to any one of claims 10 to 13, characterized in that the constant is the same for all feed steps. 15. The method according to any one of claims 10 to 13, da- ¹ ^ characterized in that the material coefficient of the workpiece is the same for all materials. 16. The method according to any one of claims 10 to 15, characterized characterized in that the machining is carried out by drilling. 17. The method according to any one of claims 10 to 15, characterized characterized in that the machining is a thread cutting process.